Modern smartphones from Xiaomi have long ceased to be just devices for calls, turning into powerful multimedia centers that require a constant connection to the network. Owners often face the need to separate personal and work contacts or take advantage of the advantageous tariffs of different telecom operators. SIM-cards at the same time, which is the standard for most models of the brand, from budget Redmi to flagship Mi.
However, despite the seeming simplicity, the setup process can raise questions for beginners, especially given the constant updates to the MIUI shell and the transition to HyperOS. Users often get confused about choosing slots, setting up their preferred map for the Internet, or are faced with the fact that the second SIM does not see the network. In this material, we will discuss all the steps, from the physical installation to the thin software configuration.
The right setup of dual-sim mode will allow you not only to save on communication, but also to manage traffic flexibly.We will consider how to avoid typical errors, why sometimes 4G disappears on the second card, and how to configure a forwarding so that you do not miss an important call, even if the main SIM card is in the area of unavailability.
Preparing for installation and choosing the right slot
Before you move on to the software settings in the menu, you need to physically correctly install the cards in the device tray.Most modern Xiaomi smartphones are equipped with a combined tray, where one of the slots can be used either for a second SIM or for a microSD memory card.
Note the shape of the notch in the tray. Usually, the SIM 1 slot has a slightly different shape or is marked with a corresponding icon, which prevents improper installation. If you use Nano-SIM cards, make sure they do not have damage to the gold contacts and chip. Dirt or oxidation of the contacts can cause the phone to stop seeing the card even if it is installed correctly.
☑️ Pre-installing check
In some older models or specific versions for the Chinese market, the slots may differ from the global versions. If one of the cards is not identified after installation, try swapping them. It is also worth considering that when using two active cards, the energy consumption may increase slightly, since the modem operates in the standby mode of two networks at the same time.
Basic setting SIM-map MIUI
Once the smartphone is turned on, the system will automatically detect new cards and prompt them to configure. If this does not happen, or you want to change the settings, go to Settings. → SIM-Maps and mobile networks: This displays all the key information about the operators connected, the signal level and the type of network used.
At the top of the screen, you'll see a list of active cards. If you click on the operator name or card number, you can go to the extended menu, and it's recommended that you give each card a clear name, like "Work" or "Personal" so you don't get confused when making calls, this is especially convenient when the lock screen or notification curtain shows which card you've been calling or texting.
Special attention should be paid to the item "Use by default", This section adjusts the behavior of the phone when outgoing actions:
- 📞 Calls: Select Always Ask if you want to decide before each set, or fix the main card.
- 🌐 Mobile Internet: Specify the card with the largest packet of traffic for automatic connection.
- 💬 SMS: configure the main card for sending messages, although modern messengers have reduced the relevance of this parameter.
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To switch cards for calls you can directly in the dialing interface, clicking on the button with the operator name under the numbers, without going into the general settings.
Remember that settings can be reset once you update your firmware or reset to factory settings. Check this section periodically to make sure your priorities remain the same. With new versions of HyperOS, the interface may look a little different, but the logic remains the same: the system seeks to simplify user interaction with two communication lines.
Mobile Internet Management and 4G Mode
One of the most common problems is that you can't use high-speed 4G internet on a second SIM card at the same time as the first. The technical limitations of many chipsets allow you to keep an active LTE connection on only one card, while the second one goes into 2G/3G mode for voice communication. This is normal behavior, but it can be controlled.
To change the map through which traffic is going, just lower the notification curtain and click on the icon Mobile Internet. The system will suggest to choose one of the available maps. It is important to understand that when you switch the Internet to a second card, the first one may temporarily lose connection to the 4G network, which will affect the loading speed of pages in the background applications using this line.
Why is the second SIM-card-less 4G?
For users who are critically important to the constant 4G On both lines, there are models with support for Dual technology. 4G. You can check for support for this feature in the hidden menu or the specifications of your device's processor. SIM-The card will be switched "Use the switch". 4G second SIM-"Cards" that must be activated.
Also worth mentioning is the Traffic Limit feature, which allows you to set consumption limits for each card separately on the mobile network menu, which is a useful tool for controlling costs, especially if the second SIM card is used with a tariff that has a limited number of gigabytes, the system will alert you when you approach the limit or automatically turn off data transfers.
| Parameter | Map 1 (Main) | Map 2 (Additional) | Recommendation |
|---|---|---|---|
| Type of network | 4G / 5G | 3G/4G (depending on model) | Mainly put in a slot with 5G support |
| Voice calls | Always ask | Always ask | It is easier to control expenses |
| Mobile Internet | Yes (main traffic) | No (reserve) | Switch manually if necessary. |
| SMS | Basic | Basic | For bank codes, it is better to fix one |
Set up notifications and work with contacts
With two numbers, it is critical to properly configure notifications to understand where the message came from or from whom the call came. Xiaomi’s standard Phone and Messages app offers a convenient color indication, with the first SIM card usually marked in blue and the second in green or orange, depending on the theme of the design.
Messages can be used to pin important dialogs or filter messages by sender. If you use a second SIM card to register for messengers (such as a separate WhatsApp or Telegram account), make sure that the app’s settings have the right map for receiving confirmation codes. Often users forget that SMS can come to a SIM that is not a priority for the Internet.
For contacts you often communicate with, you can set your preferred card to call: Open the contact, click Change or select Default for calls, and specify the number you want. Now, when dialing this caller, the phone will automatically use the selected line, bypassing the system request.
Notifications that are missed will show which card you have been called to if you were busy or your phone was silent, and you can quickly tell if you need to call back right now or if you can wait, especially if you were calling on a work number after hours.
Solving Common Problems with Defining Maps
Sometimes, when a phone sees only one card, or a second card disappears periodically ("No network"), the first step is always to reboot the device, which is a banal but effective method that allows the modem to re-register on both networks.
If the reboot didn't work, check the network type settings. → SIM-maps and mobile networks → Try changing the value temporarily for the preferred type of network, such as switching to "Only" 3G", Check the visibility of the card and then return the "Preferred" 4G". Sometimes manually logging in to the network helps solve the problem: disable automatic operator selection and select your provider from the list manually.
⚠️ Note: If the phone is writing"SIM-card not found" or "No service" after falling or getting moisture, do not try to warm up the device or knock on it.
The problem may also be the older version. SIM-The carriers change the security standards periodically, if your SIMKE is more than that. 5-7 In the years, it makes sense to contact the communication salon for a free replacement with a new one with the support of modern standards. 4G/5G VoLTE.
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In 90% of cases, the problem of the second SIM is solved by replacing the tray, cleaning contacts or rearranging cards between slots 1 and 2.
Use Dual Apps for the second SIM
Having two SIM cards often means wanting to have two accounts on popular messaging apps. The MIUI shell offers a built-in Dual Apps feature that allows you to create a full copy of an app, like WhatsApp, that will work independently of the main one.
To activate, go to Settings → Applications → App Cloning. Select the messenger you want from the list. A yellow icon (usually) will appear on your desktop, indicating a clone. When you first run a cloned application, you can register it to the second SIM card number.
This solution is more stable than third-party clones because it is integrated at the system level. However, it is worth remembering that having two active clones and two SIM cards can increase battery consumption. Background synchronization of two accounts requires processor resources.
⚠️ Note: When you delete the main application, the clone will also be deleted. If you want to save the data of the second account, first back up or unplug the cloning in the settings before deleting the original.